DIY Bio-Nitrate filter

60g, unplanted tank.
It's a long story but I discovered that my tap (country well) water was very high in nitrates 60ppm+!
Even though I was doing proper housekeeping with gravel siphoning, 50% weekly water changes and filter maintenance, I was having peculiar fish losses.
I decided to make a denitrator filter. It uses a kitchen type lock top canister, a combination of Seachem Matrix and Seachem De*Nitrate and a Tom aqua lifter pump. See Photo log.
I'm in the process now of cycling the filter/tank using Seachem Stability.
As you can see from the water test photo, Nitrates are very high. I will report on progress.

How it works... much like a canister filter on a much smaller scale, an airline siphon tube comes from the tank into one of two T's in the top. The holes for the T's were carefully drilled smaller to make for a press fit, then sealed on the inside with GE 100% silicone just to be sure. The inlet T has one end plugged with silicone so it really acts like an 'L'. Another tube attaches to the 'L' a runs down a corner under the dispersion plate to the center of the canister. The disperison plate is simply the top of the 2L Seachem Matrix jar drilled with holes. Over this goes a filter pad then the mixture of Seachem Matrix and Seachem De*Nitrate. The other T in the top center has the tube that connects to the Tom Aqua Lifter (3.5gph), then a small piece back into the tank. Very, very simple.

Neat idea, although I probably would have skipped using the De-nitrate initially so that you could better evaluate how it works at nitrate reduction. Not that the De-nitrate won't help, but you will have trouble knowing if it was just that and has nothing to do with the filter or it's design.

Neat idea, although I probably would have skipped using the De-nitrate initially so that you could better evaluate how it works at nitrate reduction. Not that the De-nitrate won't help, but you will have trouble knowing if it was just that and has nothing to do with the filter or it's design.

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I had been using about 1.5 Liters of Matrix in a dedicated AquaClear 70 filter (set to low flow of 100gph~). Although it served as a very good bio-filter, it didn't seem to do much for nitrates. The lower flow, De*Nitrate and more product seemed to be worth a try. The DIY filter has 1 liter of Matrix and 2 liters of De*Nitrate. (Matrix and De*Nitrate are the same product, de*nitrate is just smaller and requires a lower flow for denitrification.

It is my hope that with this filter and good tank/filter maintenance, if I can achieve and maintain very low nitrates, I will be able to do less frequent, lower volume water changes (even with my water) and still have a very balanced water chemistry. Along these lines, with reduced water change frequency/volume, I may periodically use activated carbon.

Neat idea, although I probably would have skipped using the De-nitrate initially so that you could better evaluate how it works at nitrate reduction. Not that the De-nitrate won't help, but you will have trouble knowing if it was just that and has nothing to do with the filter or it's design.

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Btw, it is the macro pores in the Matrix/De*Nitrite that creates the platform for the anaerobic bacteria. Aerobic bacteria colonies exist on the surface using the oxygen, while anaerobic bacteria can colonize within the pores where little/no oxygen exists.

Btw, it is the macro pores in the Matrix/De*Nitrite that creates the platform for the anaerobic bacteria. Aerobic bacteria colonies exist on the surface using the oxygen, while anaerobic bacteria can colonize within the pores where little/no oxygen exists.

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You're missing the point of my comment. If a nitrate reactor is designed properly the entire chamber(or nearly so) is anaerobic and so there isn't any need for special media. Anything with surface area will do. The fact that De-nitrate is designed to work anywhere in regular filters as your comment points out, means that you can't be sure if your reactor is creating the correct environment or if it's just that you have enough de-nitrate to do the job. I'm not saying it isn't a good choice for media, just that it makes it hard for you to evaluate the efficiency of your design.

I agree with Sub, sounds like maybe R/O might be a good investment...nitrates are not good for people, either. Do you have a shallow well, or runoff from agriculture in your area?Love your filter by the way! Such a simple design, and so clever

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Thank-you! I did not know I had such high nitrates until recently...although it makes sense. My well is 110 feet deep, but across the road is 95 acres of a farmers field that gets organic and chemical fertilizer. As for drinking water, my wife became seriously ill over 25 years ago and although unrelated, as a precaution, we began having bottled water delivered...and have ever since.

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